4B-Elongation Index - American University of Sharjah...

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American University of Sharjah College of Engineering Department of Civil Engineering Instructor: Arshi Faridi E-mail : afaridi@aus.edu Course: CVE 202 Experiment #: 4B ELONGATION INDEX Purpose: To determine the elongation index of coarse aggregate in accordance with BS 812: Section 105.2: 1989. Background: Aggregate particles are classified as elongated when they have a length (greatest dimension) of more than 1.8 of their mean sieve size, this size being taken as the mean of the limiting sieve apertures used for determining the size fraction in which the particle occurs. The elongation index is found by separating the elongated particles and expressing their mass as a percentage of the mass of the sample tested. The test is not applicable to material passing a 6.3 mm BS test sieve or retained on a 50.0 mm BS test sieve. The particle shape and surface texture of an aggregate influence mostly the properties of freshly mixed concrete. Rough textured, angular, flaky and elongated aggregates require more water to produce workable concrete than do smooth and rounded aggregate and this affect the strength of concrete. Elongated aggregates produce harsh concrete, which is difficult for pumping, placing and finishing.
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This note was uploaded on 12/18/2011 for the course ECON 102 taught by Professor Drfcvvv during the Spring '11 term at Politechnika Wrocławska.

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4B-Elongation Index - American University of Sharjah...

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